The present invention is directed to providing a solution to the problems of visual stress induced by prolonged viewing of images on computer screens. Those of ordinary skill in the art refer to such images as pixillated. The particular problems of viewing these images are induced by: 1) lag of accommodation; 2) contrast sensitivity; 3) blue light spectrum glare; and 4) loss of convergence capability.
Varying degrees of eye strain have been observed in persons viewing pixillated images on computer screens. Persons viewing these images exhibit blurry vision at table top distances due to a combination of fatigue and a disrupted accommodative system. Another problem associated with staring at a computer screen for long periods of time without blinking is dry eyes. The normal response to dry eyes is reflexive tearing. Reflexive tearing itself can cause new glare problems in the same manner as a dry or dissected cornea. In addition, drying of the eyes due to staring at the computer screen can also lead to a condition known as red eyes. All of the aforementioned symptoms can also lead to headaches.
Glare from the computer monitor screen, room light and/or sun light can also cause other problems for the computer user. Among these problems are spasms of the pupils, headaches and cloudy vision.
Another problem that can arise is related to the poor contrast on a computer screen. The poor contrast can lead to poor discrimination of near and far fields of vision. The poor discrimination creates a melding effect that makes the processing of visual information more difficult. The effect slows the ability to correctly process visual information and slows the speed at which the computer user can work.
If a computer user engages in prolonged viewing and scanning of the computer screen with degraded visual information, fatigue of the ocular mot0r muscles in the eye will result. When these muscles become fatigued, both eyes no longer simultaneously view the exact same information. This effect in turn causes blur as the vision has an area around the muscles called panama area which, allows for the maintenance of fusion. As fusion slips away and the eyes fatigue, blur sets in. Initially, blinking will reset fusion by disrupting the slippage. As fatigue continues, blur of the vision degrades into an intolerable state of double vision.
The ability to address these problems in one lens would be most useful to computer users. There are presently over 70 million computer users in the United States alone according to a 1992 NIOSH study. As of 1995, eye doctors had treated over 15 million people with computer related vision problems. It is estimated that over 1 million additional persons per year will suffer from some sort of computer use related vision problem.
It is therefore an object of the present invention to provide a novel approach to treating computer induced visual stress. This object is achieved through the use of specific magnification to reduce symptoms of lag of accommodation and the use of a specific amount of prism to address convergence fatigue.